I have some R6 coaxial cable that runs from the alley underground and into my house to provide high speed internet and TV service. The line was cut by mistake while digging in the backyard. I've spliced it together and service is restored (yay!) but I wonder whether the splice will be OK for the long run.

  • The coaxial cable is inside a 1/2" black plastic pipe of some sort (looks like sprinkler line) as a sort of conduit.
  • There was water inside that black plastic pipe at the point where I cut into it, so the splice will definitely get wet if I leave it there.
  • I stripped the ends of the cut lines, added 2 Compression F Connectors (one on each side), and screwed those compression connectors onto a screw-on splice connector.

I haven't yet tried to pull on the coax to see if I could just run a new complete line all the way through.

4 Answers 4


If this is a house drop, the line that runs from the provider's pedestal to the house, it is going to be RG-6 cable most likely. A bit larger than one-quarter of an inch in diameter. There is a product for cable television installers that meets your description, coax in conduit, although that's a very loose description in my opinion. Ostensibly it's been created to protect the cable from digging cuts (and you can see how that worked out) and to allow pulling of replacement coax. Typically, the installation puts so many bends into the conduit that friction wins over pulling a new line into the tubing.

You state that you've spliced it, but did you use coaxial connectors including an F-81 barrel to join the connections?

F-81 barrel connector

As noted in a previous answer, you may not have enough slack to perform a single connection.

If you've not used "industry standard" connectors and had insufficient weatherproofing/waterproofing, you can be assured of poor signal (ghosting, snow/pixelation) and a quick demise to the splice.

If you've used the correct connectors and good waterproofing, you may get a few months of service from the connection.

Adhesive lined heat shrink tubing provides really good protection, but it has limitations in the underground environment, especially in wet conditions.

In twenty years of cable television service, I've performed (against company policy) underground splices of house drops. Almost always (can't think of an exception) I've had to return to replace the entire drop.

If your cable company charges you to replace a house drop, you can dig your own trench and ask them for a length of coax to replace the entire damaged run. No need to go all "sprinkler-system" on the trench. It's common to use a square edge shovel, stomp it into the ground and wiggle it fore and aft to make a v-shaped trench. Move one blade to the side and repeat until you reach your goal.

Television coaxial cable has no voltage and requires no minimum depth. If you want to ensure future protection, get big-box-store small diameter conduit and trench it in, then put a pull string inside to make the replacement easier.

You'd really want to call the cable company to make the connections at the pedestal and house demarcation box to ensure problem free service.

cable television demark box Cable Television demarcation box

cable television pedestal Cable Television pedestal


Chances are good it will oxidize if not hermetically sealed. The (presumably) steel connectors will rust, and the copper core conductor will turn green. Ultimately this could result in a failed connection.

Also, you've added quite a bit of resistance to the signal. You may see degraded performance, especially downstream of additional splitters and connectors.

  • 1
    Seems like great advice :) I had a technician come out a while ago and test the line. The signal inside the house at the modem was so high it was beyond their spec. He added a splitter with nothing on one side to reduce the signal. So...I guess if I have a weak signal then one option would be to remove that splitter?
    – greggles
    Commented Oct 4, 2018 at 18:05
  • The steel connectors are usually nickel plated, but that won't last forever. The coaxial conductor is aluminum foil with aluminum wire braid, which corrodes rather nicely when exposed to moisture. Greggles, a splitter effectively reduces the signal by half (and a tiny bit more). Removing it will indeed increase the signal levels. Usually a high inside signal means an incorrectly configured device on the main or feeder lines, but many techs (including myself) would not go looking for trouble, if there was an easy patch fix like a splitter!
    – fred_dot_u
    Commented Oct 4, 2018 at 23:30
  • If another more responsible technician discovers the imbalance and corrects it, your signals will drop in level, at which point having an easily accessible splitter is advantageous.
    – fred_dot_u
    Commented Oct 4, 2018 at 23:32

If water gets into the splice, it will certainly effect the performance of the cable. It could create a dead short, which would likely shut down the service completely, or a high impedance short, which might only affect speed and error rates.

There are waterproof direct burial splice kits available for coax. You might not have enough slack to make a splice repair - you might have to cut out a section and splice in a repair section.

  • 2
    If it's already gotten wet, the water may have wicked its way through several feet of cable, all of which will have to be replaced.
    – mrog
    Commented Oct 4, 2018 at 16:16
  • In your experience, how well do the waterproof direct burial splice kits work?
    – greggles
    Commented Oct 4, 2018 at 18:02
  • @greggles - properly applied they work very well. Commented Oct 5, 2018 at 1:43

Two long for a comment , Since you have already spliced it I would wrap the splice with a quality electrical tape or rubber linerless 130c type of splicing tape in both cases 50% overlap starting a couple of inches before and after your f fittings I have made emergency repairs where 480v lines were cut underground and wanted to go back and replace the lines but the owner said that was fine as it was a long large wire gauge run I was concerned but it has lasted for over 3 years so far and I know the water table is higher than the splice in the winter as the plant is right next to a wet land area. I used 130 linerless then electrical tape to protect the linerless.

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